Apparatus for producing cement sheets

ABSTRACT

Apparatus for producing a cement sheet, including a rotatable mould into which a cement mix is fed to form a soft, centrifugally moulded cylinder, which is then removed from the mould, divided longitudinally, and laid out flat to harden. The soft cement cylinder is removed by means of a mandrel inserted into the cylinder while in the mould. During removal from the mould, the cement cylinder is held onto the mandrel either by vacuum applied to perforations in the wall of the mandrel, or by means of a liner initially placed within the mould and which surrounds the cylinder while it is removed from the mould on the mandrel. Slitting means are provided, movable relative to the mandrel to form a longitudinal slit in the soft cylinder on the mandrel after its removal from the mould. The apparatus is particularly useful for producing small quantities of asbestos cement sheets with special laminations or surface effects. Apparatus in accordance with the invention may be used for producing sheets of flowable hardenable material other than cement.

United States Patent 11 1 Barratt 1 Nov. 20, 1973 APPARATUS FORPRODUCING CEMENT SHEETS [76] Inventor: William C. Barratt, 595 SheppardSt., Niagara Falls, Ontario, Canada [22] Filed: Jan. 3, 1973 [21] Appl.No.: 320,770

Related US. Application Data Continuation-impart 6r Ser. NO. 166,779,July 28,

1971, abandoned.

[30] Foreign Application Priority Data 2 Feb. 1, 1972 Great Britain..4712/72 [52] US. Cl 425/86, 264/86, 425/297,

51 Int. Cl. 13286 21/08 [58] Field of Search 425/86, 182, 297, 425/308,324, 425, 426, 427, 436, 435, DIG.

44, DIG. 124; 249/112; 264/86, 159, 311

Primary ExaminerH. A. Kilby, Jr. Attorney-John W. Malley et a].

[57 ABSTRACT then removed from the mould, divided longitudinally,

and laid out flat to harden. The soft cement cylinder is removed bymeans of a mandrel inserted into the cylinder while in the mould. Duringremoval from the mould, the cement cylinder is held onto the mandreleither by vacuum applied to perforations in the wall of the mandrel, orby means of a liner initially placed within the mould and whichsurrounds the cylinder while it is removed from the mould on themandrel. Slitting means are provided, movable relative to the mandrel toform a longitudinal slit in the soft cylinder on the mandrel after itsremoval from the mould. The apparatus is particularly useful forproducing small quantities of asbestos cement sheets with speciallaminations or surface effects. Apparatus in accordance with theinvention may be used for producing sheets of flowable hardenablematerial other than cement.

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I APPARATUS FOR PRODUCING CEMENT SHEETS This application is acontinuation-in-part of my United States Patent application Ser. No.166,779, filed July 28th 1971 now abandoned.

The present invention relates to apparatus for producing sheets from aflowable hardenable material such as cement, which sheets may be flatcurved or congtoured. The invention particularly relates to apparatusfor performing the process of copending Patent application Ser. No.166,778 also filed July 28th 1971. The sheets may be used either asproduced or cut to smaller sizes, for example as structural members,wall panels, or roof sections, or for decorative components such astiles, moulds, millwork or shingles.

In the known wet process for manufacturing cement sheets, andparticularly asbestos cement sheets, a large plant is required which inorder to be economical must operate on a high production basis, and sucha process is not easily adapted for producing small quantities ofspecial decorative materials.

The present invention provides apparatus which is 'suited to theeconomical production of small quantities of cement sheets, and whichcan readily be adapted to produce a wide variety of surface finishes, orother characteristics, in the cement sheets produced. The apparatusproduces the cement sheets singly, one after the other, and it is a verysimple matter to modify the operation of the apparatus betweenindividual sheets, so that a wide variety of different cement sheets canbe produced in a short time. The cement sheets can vary as to thickness,composition, colour, and the nature and shape of the surface finish. Theapparatus thus is very suitable for producing a lot of differentcomponents, having different shapes and surface finishes, for a singlebuilding. The apparatus used in accordance with the invention does notrequire a large investment or take up a large amount of space, so thatit is very suitable for location in the locality where building istaking place. Furthermore, the nature of the process used gives a highstrength product due to avoidance of excess water, uniformity of wallthickness, high density and predetermined directional resistance tostresses. In

the case of cement reinforced by fibres, such as asbestos cement,additional strength is given by good orientation and formation offibres. Also, the process operates with very little waste.

In the process described in copending application Ser. No. 166,778, acement sheet is produced by a centrifugal casting method, the cement mix(including water) being fed into a rotatable cylindrical mould and spunto distribute the mix evenly around the mould wall to shape the mix intoa hollow cement cylinder. One end plate of the mould is removable toallow for axial removal of the cement cylinder, and in order to effectthis removal a cylindrical mandrel is inserted into the mould to engagethe inner surface of the cement cylinder, which is then withdrawn on themandrel. After removal, and with the cement cylinder still in the softor flaccid state, the cement cylinder is divided longitudinally and theresultant sheet is laid out onto a flat or curved surface and allowed toharden.

The present invention provides apparatus for performing this process,which comprises, firstly, a cylindrical mould mounted for rotation on ahorizontal axis and having a removable end plate, the mould and endplate being such that a cylindrical body of cement or other materialformed within the mould can be exgageable with the inside surface of acylinder of the material as formed in the mould. Mounting means for themandrel are provided which allow movement thereof axially into the mouldand which also allow rotation after removal from the mould, tofacilitate unrolling the final product. The mounting means may includehandling means such as cranes or hoists, but preferably a specialcarriage is provided. Means are provided for holding the cylinder on themandrel during removal thereof from the mould, as described more fullybelow. Also, slitting means are provided for forming a longitudinal slitin a cylinder of the material held on the mandrel outside the mould,although as an alternative to slitting means the mould may be providedwith an inwardly projecting member arranged to form a longitudinaldivision in the cylinder formed in the mould. Suitable slitting meansare an upwardly projecting blade, or a wire band saw, preferably appliedto the underside of the soft cylinder of cement or other material whileit is held on the mandrel. The apparatus also includes a surface forreceiving a soft sheet of the material released from the mandrel, withmeans being provided to allow relative transverse movement between themandrel and this surface with rotation of the mandrel to facilitateunrolling of the sheet from the mandrel.

The means for holding the cylinder onto the mandrel may include ports inthe cylindrical surface of the mandrel, and conduit means connectingthese ports to a source of vacuum, so that during removal of thecylinder this can be held onto the mandrel by vacuum. The mandrel mayalso be connectable to a source of compressed air to give release of thecylinder when required.

Alternatively, or additionally, the apparatus may ini clude a liner forexample of sheet metal or rubber, bendable to form a cylindrical surfacewithin the mould, and having a longitudinal division so that it may belaid out flat with the sheet of material formed in the mould. The linermay have opposed edge portions which are adjacent while the liner is inthe mould, these opposed edge portions having means for connecting themtogether when the mandrel is inside the cylinder so that the liner canassist in holding the cylinder onto the mandrel. The liner edge portionsmay be directly connected together, by means of a clip. The liner maybecome incorporated in the final product, or may be separated from thefinal sheet and re-used. The adjacent edge portions of the liner may bespaced apart (while surrounding the cylinder) so as to allow thecylinder to be slit through the gap between the edge portions.

The process and apparatus will be particularly described by way ofexample with reference to the accompanying drawings in which:

FIG. 1 is a partly sectioned elevation of a first type of centrifugalmould for use in accordance with the invention,

FIG. 2 is a cross-section through the mould of FIG.

FIG. 3 is an elevation of a mandrel, FIG. 4 is a cross-section throughthe mandrel on line 4-4 of FIG. 3,

FIGS. 5 and 6 show details of the mandrel in crosssection and sideelevation respectively,

FIG. 7 is a sectional elevation through the mould with the cementcylinder and mandrel in place,

FIG. 8 is a view of the mandrel in the last stage of the process,

FIGS. 9 and 10 show variations of the basic method which produce acement sheet with an exposed particulate surface,

FIGS. 11 and 12 are edge views of special cement sheets produced inaccordance with the invention;

FIG. 13 is a partly sectioned elevation of a second type of centrifugalmould for use in accordance with the invention,

FIG. 14 is a cross section on lines 14-14 of FIG. 13 showing details ofliner locking means,

FIG. 15 is a partly broken away view of a modified mandrel for use withthe mould of FIG. 13,

FIG. 16 is a cross-sectional view of the modified mandrel on lines 16-l6of FIG. 15,

FIG. 17 is a partly sectioned view of the mould of FIG. 13 with themodified mandrel in place,

FIGS. 18a, 18band 18c illustrate modified apparatus for slitting, layingout and curing the cement sheets,

FIG. 19 shows a cross-sectional view of part of a further modifiedmandrel engaging a cement cylinder within a modified mould, and

FIG. 20 shows an end view of a mould with modified means for removingwater from the cement.

Referring to FIGS. 1 and 2, the apparatus includes a rotatablecentrifugal mould indicated generally at 10. The mould has a cylindricalwall 12, which is of sheet metal and is perforated with 1/16 inchdiameter holes spaced apart on 1 inch centres circumferentially andaxially of the mould; these holes allow outflow of water duringspinning. The mould wall 12 is reinforced by an end ring 14 securedwithin one end of the wall, and which is of a thickness greater than thecement cylinder to be spun; and also by reinforcing rings or tires 15which rest on four rollers 16. The rollers 16 are carried by twoparallel horizontal shafts 17, supported in bearings 18, and one ofthese shafts is driven by a motor and gearbox combination 19. When themotor is operated to drive the shaft 17, the frictional contact betweenrollers 16 and the tires 15 causes the mould to rotate about itshorizontal axis.

The mould has a fixed end plate 21 and a removable end plate 22. Thefixed end plate 21 is of annular form having a central aperture 21awhich is large enough to allow fluid cement material to be fed into themould by feeding means in the form of a charging head 23 to bedescribed. The fixed end plate 21 is held by nuts on threaded studs 21bwelded to the mould wall, and is removed only for maintenance or mouldalterations.

The removable end plate 22 is mounted on an axially projecting stubshaft 26, which is carried in a bearing 27 supported at the end of aswing arm 28. The swing arm is pivoted at 30 and is rotatable from theclosed position of FIG. 1 to the open position of FIG. 7 by means of apower cylinder 31. The inside of end plate 22 is provided with a centrallocating ring 33 having an inner surface which flares outwardly towardsthe other end of the mould, and which serves to support and locate oneend of the charging head 23.

It will be apparent that the end plate 22 need not entirely cover theend of the mould, but may instead pro vide a cover over an annularportion only, of radial thickness greater than that of the cylinder tobe spun therein.

The charging head 23, as shown in FIG. 1, is mounted on a supportcarriage 24 mounted on rails 24a adjacent that end of the mould with thefixed end plate. These rails allow movement of the charging head fromthe operative position of FIG. 1, in which the charging head extendsthrough the fixed end plate 21, to a retracted position in which thecharging head is withdrawn clear of the mould.

The charging head comprises a horizontally extending support membersomewhat longer than the mould in the form of a parallel sided channel34 open at its lower end and reinforced at its top by a horizontal plate34b. At its outer end (remote from the carriage 24) the plate 34bcarries a positioning pin 35, which, when the charging head is in theposition of FIG. 1, locates in the locating ring 33 and assists insupporting the outer end of the charging head. The support membercarries at one side a cement feed pipe 36, having downwardly extendingdistribution pipes 36a spaced along the pipe 36 at 1 foot spacing. Belowthe lower ends of pipes 36a there is provided a curved shutter 38 which,when in the closed position shown in broken lines, co-operates with theoutside of the channel 34 to provide a trough suitable for retaining aquantity of particulate material. The shutter 38 is mounted on radialarms 39 pivoted to the support member at 80, and pivotally movablerelative to the support member by fluid cylinder 81 to move this shutterinto the open position shown in full lines, allowing material held inthe shutter to be released onto the inside of the mould or to be feddirectly into the mould from discharge pipes 36a.

The channel 34 accommodates a hollow, parallel sided member 83vertically slidable therein under the control of hydraulic cylinder 84.The lower end of member 83 has a curved corner joining the vertical sideof the member 83 with the horizontal lower edge-- thereof, this curvedcorner facing the direction of rotation of the mould which direction isindicated by the arrow. This curved comer and the adjacent surfaces ofmember 83 form spreader means 86 having a hard facing and capable ofcontacting the inner surface of a hollow cylinder of material being fedinto the mould, to assist in evenly spreading the material within themould. During the stage in which material is being fed into the mouldvia pipes 36a, the spreader means is caused to rise at a steady rateunder control of fluid cylinder 84.

The member 83 also incorporates means for removing water from within thecentre of the cylinder of material being spun within the mould, in theform of a skimmer 88 which is movable by fluid cylinder 89 between aretracted position in which it does not extend below the surface of thespreader means, to an extended position as shown in broken lines inwhich it projects below the lower surface of the spreader means. Theskimmer 88 has an opening facing the direction of rotation of the mould,and which communicates with a water discharge pipe 90 extending alongthe member 83.

The member 83 also incorporates a vibrator 92 mounted on the inside ofthe spreader means and arranged to cause'vibration of the spreader meansfor compacting material in the mould.

The apparatus also includes a special cylindrical mandrel 40, which isshown in FIGS. 3 to 7. The mandrel has a cylindrical outer wall 400, thediameter of which is selected so that this can be inserted into a cementcylinder which has been formed in the' mould.

The diameter of the mandrel is such that the cylindrical surface of thisis engageable with the inside surface of the cement cylinder withoutdimensional change of the latter. An outer end of the mandrel is closedby an end plate 41 (see FIG. 7), to the centre of which is welded aguide member 42 in the form of a tubular shaft. The guide member 42 islonger than the length of the mould, so that it can be used to guide themandrel into the mould. The other end of the mandrel has a shorter shaft41a projecting axially therefrom.

The mandrel wall 40a is pierced by longitudinal rows or ports 43, andeach row of ports communicates with a longitudinal channel-44 within themandrel. These longitudinal channels, which are shown in cross-sectionin FIGS. 4 and 5, are constituted by channel members 45 having theirouter edges welded to the inside of the wall 40a, each row of ports 43being centrally positioned along a channel member. FIGS. 5 and 6 showvalve means 47 which allow one end of each channel '44 to beindividually placed in communication selectively with a vacuum headertube 48 or a compressed air header tube 49. These header tubes 48 and49, which are shown in FIGS. 5 to 7, are toroidal tubes of equaldimensions positioned close together near to one end of the mandrel, andconnected by radial conduits outer surface fixed to a channel member 45.The valve body has two radial bores 57 and 58 leading respectively fromheader tubes48 and 49 into the channel 44,

and a valve member 59 is slidable in an axial bore in the valve body tocontrol flow of air through these radial bores. The valve member 59 hasa central recessed portion 60; in the position shown in FIG. 6 thisrecessed portion-is between the radial bores 57 and 58 and the valvemember prevents flow of air through either bore.

By pulling-out an extension'61 of the valve member, the

recessed portion 60 is brought into registry with the bore 57, so thatthe channel 44 is put into communication with the source of vacuumthrough header 48 and hose 52; and when the valve member is pushedinwardly to bring recessed portion 60 into register with bore 58 thenthe channel 44 is placed in communica- -tion with the source ofcompressed air via bore 58,

header 49, and hose 53.

A curved operating member may be rotatably mounted at the outer end ofthe mandrel, and arranged to engage the valve member as it rotatesrelative to the mandrelto move these from the vacuum position to thecompressed air position.

FIG. 7 is a view of the mould with a spun cement cylinder in place, andwith the mandrel inserted to contact the inner surface of the spuncement cylinder, which is mandrel into the mould, and must also allowrotation of the mandrel by at least almost 360 with relative transversemovement between the mandrel and the surface which receives the cementsheet, for releasing and unrolling the cement sheet from the mandrel inthe manner to be described.

The only other essential parts of the apparatus are slitting means forforming a longitudinal slit in the cylinder of soft cement held on themandrel, after removal from the mould; means for causing relativemovement between the slitting means and the mandrel to form thelongitudinal slit, and a surface onto which the cement sheet can be laidafter removal from the mandrel.

In the simplest apparatus, the slitting means may be a blade, such asblade 73 of FIG. 8, projecting upwardly in fixed position, andassociated with the receiving surface 72, the blade having a length atleast equivalent to that of the mandrel and having a width greater thanthe thickest sheets to be produced. In this embodiment, the means forcausing relative movement between the slitting means and the rnandrelwill be the handling or mounting means of the mandrel which allow thisto be lowered onto the blade 73. The receiving surface may be providedby a pallet which can be located suitably in relation to the slittingblade 73 for receiving a cement sheet removed from the mandrel, andwhich is then removable to another location where the cement sheeth'ardens. The receiving surface 72 may be a plain flat surface orcurved, or may have a relief design thereon for producing acorresponding relief design in the cement sheet. In the latter case, theapparatus will also include a standard type of hydraulic or other pressby means of which pressure can be applied to the top surface of thecement sheet to cause the lower surface 1 to assume the shape of thepallet surface.

The process of the invention will now be particularly described withreference to FIGS. 1 to 8.

Operation of the apparatus in the simplest manner, to I produce a cementsheet without incorporation of fibres and without laminations, will nowbe described.

The charging head 23 is firstly advanced into the mould on rails 24a, tothe position of FIG. 1, and the removable end plate 22 is closed. Thecylinder 84 is actuated to bring the spreader means 86 close to themould surface, and cylinder 81 is operated to open the shutter 38 to theposition shown in full lines. A cement mix is then fed onto the mouldsurface via the pipes 36 and 36a, and simultaneously the cylinder 84 isoperated to raise the spreader means 86 gradually, so that thesemaintain contact with the cement mix and ensure that this is spreadevenly within the mould. The cement mix is fed in while wet (with aboutpercent water) and rotation of the cylinder at a peripheral speed of1200 ft/min. for about five minutes causes the wet cement to form acylindrical layer of uniform wall thickness on the inside of the mould.The centrifugal effect also concentrates-and compacts the solidparticles of the mix in the outer parts of the cement layer, and excesswater which does not flow out of the perforations in the wall of themould is forced to the center of the mould and flows out of this duringa de-watering stage.

The use of a cement mix containing only 70 percent water is in contrastto other methods where more than 90 percent excess water is required.

The de-watering stage is reached after the material has spunsufficiently to compact the solids into cylindriical form and to form aninner layer of excess water. This takes about one minute. At this stagethe cylinder 89 is operated to cause skimmer 88 to protrude from thelower surface of the spreader means, and cylinder 84 is operated to movethe member 83 downwardly until the skimmer contacts the layer of waterwithin the mould. The water is then skimmed off by pumping this throughdischarge pipe 90. In the final stages of dewatering, the spreader means86 is brought into contact .with the cement cylinder, and the vibrator92 is activated to cause vibration of the spreader means, and compactionof the cement, while the mould continues to spin.

At this stage rotation of the mould is stopped, and the end plate 22 isremoved to the position shown in FIG.

- 7 by operation of cylinder 31. The cylindrical mandrel 40 is thenpositioned in the mould, by suitable handling means, into the positionof FIG. 7.

When the mandrel is in place (as shown in FIG. 7) the valve members 61are operated to connect the channels 44 to the source of vacuum so thatthe cement cylinder, which is already contacting or almost contactingthe mandrel surface, is forced against the surface by atmosphericpressure. The mandrel is then withdrawn from the mould, and subsequentlythe cement cylinder is slit by being lowered, while still on themandrel, onto the blade 72 so that this slits the cylinderlongitudinally. The mandrel carrying the cement cylinder is then rolledalong, i.e., moved transversely over the surface 72 while beingsimultaneously rotated, so that the cement sheet is laid out on thesurface 72 (FIG. 8) During removal of the cement sheet the valve members61 are operated successively to cause the lowermost channels 44 of themandrel (e.g. channels 44a and 44b of FIG.

8) to be connected to a source of positive air pressure to assist theremoval of the cement sheet from the mandrel. The valve members 61 ofchannels from which the cement sheet has been removed are returned tothe neutral position of FIG. 6.

Preferably, the cement sheet so produced is subjected to a finalpressing operation as between the platens of a press, this givinggreater strength and density to the product. Subsequently, the cementsheet is hardened by curing in known manner. Also, the cement sheet maybe rolled off the mandrel onto a platen having a relief design, thecement sheet being pressed onto the platen to reproduce the design.

It may be noted that the mandrel not only facilitates removal of thecement cylinder from the mould, and the slitting of this, but alsoenables the cement sheet to be rolled and compacted while being laidout.

In another process using the apparatus of the invention, the materialfirst fed into the mould is a particulate material mixed with cement andwater or any suitable bonding agent. The particulate material may beaggregate, or particles of glass, or metal, or of plastics material. Asbefore, this particulate material is fed in while the mould is rotating,and rotation is continued until the material has formed a uniform layerwithin the mould.

The shutter 38 provides convenient means for supplying the particulatematerial to the inner surface of the mould. Before the charging head 23is advanced into the mould, the shutter 38 is closed by cylinder 81, andthe trough formed between shutter 38 and the side of member 34 is filledwith the particulate material.

'After the charging head is in position in the mould the shutter 38 isopened to release the particulate material onto the inner surface of themould. This material is then evenly spread in the mould by operation ofthe spreader means 86. Subsequently, a cement mix is fed into the mould,and the mould is spun to produce a flaccid laminated cement cylinderhaving the particulate material bonded to the outer layer. The cementcylinder is removed from the mould on the vacuum mandrel, as describedabove, slit, and the cement sheet laid out to harden. The surface of thecement sheet may then be polished to provide a flat surface in which theparticulate material is exposed.

Instead of being a plain flat surface, e.g., the surface of a pallet,the receiving surface may be such as to be capable of becoming bonded tothe soft cement sheet. One example of this is illustrated in FIG. 9,which shows a soft cement sheet being laid out onto a bed of aggregatematerial. Bonding of the soft cement sheet to the granular material isachieved firstly by using the mandrel in the manner of a roller, andthen by pressing the resultant product between the platens of a press.The final product is illustrated in FIG. 11. Instead of using a bed ofparticulate material, the soft cement sheet can be laid out on a sheetalready prepared according to the process, so that a thick laminate canbe built up.

In the process of FIG. 10, an asbestos cement sheet which has beenproduced in accordance with the invention, as described, is laid outflat on a pallet, but before the sheet hardens aggregate material issprinkled on the sheet, and pressed in, and the sheet is then allowed toset.

FIG. 12 shows a portion of a cement sheet having a sculptured or reliefdesign surface. This can be made by laying out a soft sheet onto apallet having a corresponding relief design surface, and pressing thesoft sheet into place by means of a press.

Also, instead of the mandrel being moved transversely over the receivingsurface, the surface may be arranged on a carriage for movementunderneath a stationary, but rotatable, mandrel.

Additionally, cement sheets with liners bonded thereto may be producedby inserting a liner into the mould before adding the cement, so thatcement cylinder becomes bonded to the liner. The bond can bestrengthened by chemical bonding with a latex product such as Albitol(registered trade mark), applied to the inner surface of the liner. Agap may be left between the adjacent edges of the liner, to allow forslitting by the blade 73. Alternatively the liner itself may forrn thelongitudinal division in the cement cylinder as particularly describedin co-pending Patent application Ser. No. 166,780. Liner materials maybe of metal, plastics or rubber.

The liners used may be plain and imperforated, in which case anon-perforated mould would be used and all the excess water would beremoved from the centre of the hollow cylinder produced. A plain linermay be used with the vacuum mandrel described or with the differenttypes of apparatus shown in FIGS. 13 to 18.

However, one type of liner which is particularly useful with theperforated mould just described is a wire mesh liner having its surfacemainly formed of a fine wire mesh of about 75 wires to the inch (bothways), and similar to the wire mesh or wire cloth used on paper-makingmachines of the Fourdrinier type. This wire mesh liner when used in themould having a perforated cylindrical wall, allows a large amount ofwater to be removed by centrifugal action during spinning, thusresulting in a dryer, denser and stronger product than that producedwith a plain liner. The liner is normally 'stripped from the cementsheet before this hardens, and is re-usable. The wire mesh may be usedin conjunction with other laminating steps described for example a layerof aggregate, or exposed particles of glass or metal may also beincorporated in the cement sheet. The cement sheets produced inaccordance with this invention can be further treated by drying whenhard at temperatures of 105C or higher, soaking in a liquid monomer suchas methyl methacrylate, and curing it to polymerize the monomer.Polymerization can be achieved by irradiating the impregnated cement orby heating the cement to 75C for 2 hours with 2 percent benzoyl peroxideadded to the monomer as a catlyst. This process gives much improvedphysical properties to the cement sheet, and also makes it impermeable.

A different form of apparatus for performing the same basic process, butin which the mandrel is fully rotatable when inserted in the mould, willnow be described with reference to FIGS. 13-18.

FIGS. 13 and 14 show moulding apparatus generally similar to that ofFIGS. 1 and 2, but adapted for use with the modified form of mandrelshown in FIGS. 15

and 16. 1

The apparatus of FIGS. 13 and 14 is similar to that previously describedin having a rotatable mould with a cylindrical wall 112 held by rings115 resting on rollers 116 mounted on shafts 117 driven by a motor andgearbox combination 119. Unlike in the first embodiment, however, themould wall 112 is not perforated.

The dimensions of the mould are about ft (3 meters) length and about 6ft (1.8 meters) in diameter. The mould has a removable end plate 122which again is the same as that of the first embodiment. At the end ofthe v mould opposite the plate 122 however the construction is differentfrom the first embodiment, in that it incorporates an axially movableannular member 121 hereinafter referred to as a void ring, which willnow be described.

The void ring 122 is of channel form, having an outwardly facing openingengaged by an annular plate 180 which is bolted to the end flange of themould. The void ring is movable axially of the mould between thepositions shown in FIGS. 13 and 17, and sealing means 181 provide a sealbetween the inner flange of the ring and the inner surface of the mould.The void ring 121 has a radial dimension greater than that of thethickest cylinders to be spun within the mould, and has interiordimensions large enough to allow space for entry of the charging head123 which is identical to the charging head 23 already described withreference to the first embodiment, and which is shown in cross sectionin FIG. 14.

FIG. 14 also shows a special form of liner 170 used in this secondembodiment. This liner is a sheet of abrasion resistant rubber ofone-half inch (12 mm) thickness sufficiently flexible to form a cylinderlining the mould as shown. The liner has opposite edge portions whichare adjacent while the liner is in the mould, the edge portions beingbonded to sheet metal edge pieces 171. The edges of the liner extendbeyond the edge pieces 171 to form a seal preventing cement or othermaterial from passing between the edge pieces 171. The edge pieces 171are provided with radially outwardly directed flanges 172, and the outeredges of these flanges have lips 173 bent back parallel to the linersurface and forming a recess therewith. The recesses are engageable bythe inwardly directed jaws of a locking clip 175, the cross-sectionalform of which is shown in FIG. 14, and which is accommodated in asuitably shaped longitudinal groove 176 in the mould surface. The clip175 thus co-operates with the edge pieces 171 to hold the edge portionsof the liner together when the cylinder and liner are removed togetherfrom the mould, as will be described, thus holding the cement cylinderon the mandrel when removed from the mould. To facilitate removal fromthe mould, the outside surface of the liner, and the inside surface ofthe mould, are coated with polytetra-fiuoroethylene.

The modified mandrel used with this mould is an expanding mandrel asshown in FIGS. 15 and 16. The mandrel includes a cylindrically curvedsurface formed by a slightly flexible metal plate 141, the longitudinaledges of which are close together when the plate 141 is unstressed andis at its minimum diameter as indicated in full lines in FIG. 16. Theplate 141 has an annular end flange 142 at one end, and is capable ofbeing expanded by means to be described to the condition shown in brokenlines in FIG. 16, the amount of radial expansion being greater than theradial depth of flange 142.

The mandrel is mounted on a tubular shaft 144 carried at its inner endby a rail mounted carriage 148, the carriage allowing axial movement ofthe mandrel into the mould and also allowing free rotation of the shaft144. The shaft 144 has an extension 145 at the outer end of the mandrel(i.e., that remote from the carriage 148), which serves a purpose to bedescribed. The shaft 144 carries two axially spaced expandingarrangements 151 and 152 by which the plate 141 is connected to theshaft 144. Each expanding arrangement comprises two opposed pairs ofgussets 154 welded to shaft 144, and two symmetrically arrangedtriangular crank members 155 each having a first corner pivoted at 156to gussets 154, a second corner pivoted to gussets 157 which are weldedinternally to plate 141 near to the longitudinal edges thereof, and athird corner pivotally connected by links 158 to gussets 159. The crankmembers 155 of expanding arrangements 151 and 152 are connected formovement together by plate 155a. Also, both crank members 155 and links158 are of channel form having parallel side plates or flanges connectedby a web. The gussets 157 are welded to the inside of plate 141 at 10-cations spaced away from gussets 157, being on the opposite side of aplane through pivots 156 from these gussets 157. The spacing betweenadjacent gussets 157 and 159 is roughly equivalent to that between thetwo gussets 159, this spacing being of the order of 100 to 120 of arcsubtended at the axis of shaft 144. The two crank members 155 arearranged to be urged apart by a pneumatic cylinder 161, this cylinderbeing connected by a flexible conduit 162 via a rotary valve 163

1. Apparatus for forming into sheet form a flowable hardenable materialsuch as a cement mix, comprising: a. a cylindrical mould mounted forrotation on a horizontal axis and having a removable end plate, saidmould and end plate being such that a cylindrical body formed within themould can be extracted by sliding without dimensional change afterremoval of said end plate; b. means for feeding said material directlyonto the inner surface of said mould or onto a liner therein, c. amandrel movable axially into the mould through the end of the mouldhaving the removable end plate, said mandrel having a cylindricalsurface engageable with the inside surface of a cylinder of the materialas formed within the mould by spinning, d. mounting means for saidmandrel allowing movement thereof axially into the mould and alsoallowing rotation thereof after removal from the mould, e. means forholding said cylinder on the mandrel during removal thereof from themould, f. slitting means for forming a longitudinal slit in a cylinderof the material held outside the mould on said mandrel, g. means forcausing relative movement between said slitting means and said mandrelto form said longitudinal slit, and h. a surface for receiving a softsheet of the material released from the mandrel, means being provided toallow relative transverse movement between said mandrel and said surfacewith rotation of the mandrel to facilitate unrolling of the sheet fromthe mandrel.
 2. Apparatus according to claim 1 further comprisingspreader means mounted for movement radially of the mould to contact theinterior surface of material being spun in said mould to assist inevenly spreading said material.
 3. Apparatus according to claim 3further comprising a vibrator attached to said spreader means arrangedto cause vibration of said spreader means for compacting the material inthe mould.
 4. Apparatus according to claim 1, further comprising meansfor skimming water from within the cylinder of material being spunwithin the mould.
 5. Apparatus according to claim 1, wherein saidmounting means for the mandrel permits free rotation of the mandrel wheninserted into the mould.
 6. Apparatus according to claim 5, whereininterengaging means are provided on said mandrel and on said mould tocause the mandrel to rotate with the mould upon insertion therein. 7.Apparatus according to claim 1, wherein said mounting means for themandrel includes shafts extending axially from each end of the mandrel,carriage means mounting one of said shafts and allowing axial movementof the mandrel into the mould, and horizontal track means fortransversely mounting said shafts after removal of the mandrel from themould, said track means being disposed at opposite sides of said surfacefor receiving the sheet of material and allowing rotation and sliding ofthe shafts thereon.
 8. Apparatus according to claim 7, wherein saidtrack means are vertically movable in unison whereby successive sheetsof the material may be laid down at successively higher levels to form apile.
 9. Apparatus according to claim 1 wherein said mould includes anannular member situated in said mould so as to define an end of saidcylinder remote from that end adjacent the removable end plate, saidannular member being movable axially of the mould and away from the endof said cylinder formed therein, and wherein said means for holding thecylinder on the mandrel includes extracting means contractible to theinternal diameter of a cylinder formed within the mould and expandibleinto a space formed between said annular member and the cylinder onmovement of said member away from thE formed cylinder, whereby the saidextracting means can engage the end of the cylinder remote from theremovable end plate to hold the cylinder on the mandrel while themandrel is withdrawn from the mould.
 10. Apparatus according to claim 1,wherein said means for holding said cylinder on the mandrel includesports in the cylindrical surface of the mandrel and conduit meansconnecting said ports to a source of vacuum, valve means being providedfor disconnecting selected ports during unrolling of the sheet from themandrel.
 11. Apparatus according to claim 1, wherein said slitting meansextends along the full length of a cylinder of material held by themandrel.
 12. Apparatus according to claim 11, wherein said slittingmeans is a blade.
 13. Apparatus according to claim 11, wherein saidslitting means is a wire band saw.
 14. Apparatus according to claim 1,further comprising a liner of sheet metal, plastics, or rubber, bendableto conform to the inner surface of the mould and capable of being laidout flat with the sheet of material formed in the mould, said linerhaving opposite edge portions which are adjacent while the liner is inthe mould, said opposite edge portions having means allowing these edgeportions to be connected together so that the liner can assist inholding the cylinder on the mandrel.
 15. Apparatus according to claim14, wherein the opposite edge portions of the liner include outwardlydirected flanges which flanges are spaced apart while the liner is inthe mould so that after extraction from the mould the cylinder ofmaterial can be slit while the liner is still in place.
 16. Apparausaccording to claim 15, wherein said apparatus further includes clipmeans adapted to engage said outwardly directed flanges of the linerwhen the cylinder is being removed from the mould, said clip means beingremovable to allow said slitting means to pass between the liner edges.17. Apparatus for forming into sheet form a flowable hardenable materialsuch as a cement mix, comprising: a. a cylindrical mould mounted forrotation on a horizontal axis and having a removable end plate, saidmould and end plate being such that a cylindrical body formed within themould can be extracted by sliding without dimensional change afterremoval of said end plate; b. means for feeding said material directlyonto the inner surface of said mould or onto a liner therein, c. amandrel movable axially into the mould through the end of the mouldhaving the removable end plate, said mandrel having a cylindricalsurface engageable with the inside surface of a cylinder of the materialas formed within the mould by spinning, d. mounting means for saidmandrel allowing movement thereof axially into the mould and alsoallowing rotation thereof after removal from the mould, e. means forholding said cylinder on the mandrel during extraction thereof from themould, said holding means including ports in the cylindrical surface ofsaid mandrel and conduit means connecting said ports to a vacuum source,f. means for forming a longitudinal division in said cylinder of thematerial to allow the material to be laid out as a sheet, and g. asurface for receiving a soft sheet of the material released from themandrel, means being provided to allow relative transverse movementbetween said mandrel and said surface with rotation of the mandrel tofacilitate unrolling of the sheet from the mandrel.
 18. Apparatusaccording to claim 17, wherein said ports are connected to said vacuumsource via valve means which allow selected of said ports to bedisconnected from the vacuum source during unrolling of the sheet. 19.Apparatus for forming into sheet form a flowable hardenable materialsuch as a cement mix, comprising: a. a cylindrical mould mounted forrotation on a horizontal axis and having a removable end plate, saidmould and end plate being such that a cylindrical body formed within themould can be extracted by sliding without dimensional chanGe afterremoval of said end plate, b. means for feeding said material directlyonto the inner surface of said mould or onto a liner therein, saidfeeding means including conduit means having a plurality of outletsspaced along the mould, c. spreader means mounted for movement radiallyof the mould to contact the interior surface of material being spun insaid mould to assist in evenly spreading said material, d. means forskimming water from within the cylinder of material being spun withinthe mould, e. a mandrel movable axially into the mould through the endof the mould having the removable end plate, said mandrel having acylindrical surface engageable with the inside surface of a cylinder ofthe material as formed within the mould by spinning, f. mounting meansfor said mandrel allowing movement thereof axially into the mould andalso allowing rotation thereof after removal from the mould, g. meansfor holding said cylinder on the mandrel during removal thereof from themould, h. means for forming a longitudinal division in said cylinder ofmaterial, whereby said cylinder can be removed from said mandrel andlaid out as a flat or curved sheet.
 20. Apparatus according to claim 19,wherein said spreader means is attached to a vibrator to cause vibrationof said spreader means for compacting the material in the mould. 21.Apparatus according to claim 1, wherein said mandrel has a cylindricalsurface formed by a curved metal plate, said metal plate beingexpandible to contact the inner surface of a cylinder of the materialheld within the mould and said metal plate having longitudinal edgeswhich are spaced apart when the plate is expanded, whereby said slittingmeans may be positioned to pass between said longitudinal edges afterslitting the said cylinder.